Photochemical Methods and Photoactive Compounds for Modifying Surfaces

ABSTRACT

Compounds and methods for controlling the surface properties are described. Compounds of the invention can form radicals upon exposure to irradiation, which can then react with nearby molecules to alter the surface properties of various substrates. The invention can provide surfaces that are resistant to dewetting, surfaces that have immobilized molecules such as carbohydrates and polymers immobilized, and surfaces that have metals deposited on the surface. The invention can be utilized in a wide range of application, such as sensors, microreactors, microarrays, electroless deposition of metals, and the like.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. patent application Ser.No. 13/416,968, filed Mar. 9, 2012, as a continuation of U.S. patentapplication Ser. No. 11/595,292, filed Nov. 9, 2006 and issued as U.S.Pat. No. 8,158,832, which claims the benefit of the filing dates of U.S.Provisional Application No. 60/735,402, filed on Nov. 9, 2005, and U.S.Provisional Application No. 60/776,096, filed on Feb. 23, 2006, both ofwhich are incorporated by reference herein in their entireties.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Work described herein may have been supported by, or in part by, U.S.Army Research Laboratory and the U.S. Army Research Office undercontract/grant number DA W911NF-04-1-0282 and in part by the NationalScience Foundation under grant numbers DMR-02-14263, IGERT-02-21589,CHE-04-15516, and RF CUNY #404340001A. The U.S. Government may havecertain rights in the invention.

INCORPORATION BY REFERENCE

The disclosures of all patents and publications referenced in thisapplication are hereby incorporated by reference into this applicationin their entireties in order to more fully describe the state of the artas known to those skilled therein as of the date of the inventiondescribed and claimed herein.

COPYRIGHT NOTICE

The disclosure of this patent document contains material, which issubject to copyright protection. The copyright owner has no objection tothe facsimile reproduction by anyone of the patent document or thepatent disclosure, as it appears in the Patent and Trademark Officepatent file or records, but otherwise reserves all copyright rightswhatsoever.

BACKGROUND OF THE INVENTION

In many applications, control of the surface properties is important.For example, controlling the dewetting properties of thin polymer filmson an organic or inorganic substrate are important in numerousapplications such as sensors, coatings, adhesives, resist layers,lubricating surfaces, and microelectronics. A smooth surface is thoughtto be wetted by an adsorbed species when van der Waals interactions atthe substrate-liquid, liquid-air, and substrate-air interfaces allow theliquid to spread on the surface such that the contact angle is zero orvery close to zero. When a thin film is cast on a nonwettable surfacefor which the interfacial tensions do not favor wetting, dewetting canoccur, a process in which the film retracts from the surface, typicallyforming holes.

Currently, thin amorphous polymer films, such as polystyrene films, areapplied to a surface and vitrified to stabilize the film. However, suchglassy films are metastable and can spontaneously dewet when exposed toa solvent vapor or heated above the glass transition temperature. Suchdewetting of films after exposure to solvent vapor is a current problemin developing sensors to detect nerve agents.

Control of surface properties can also enable new fields of study. Forexample, glycomics (a field that explores the information content ofcarbohydrates) has emerged recently. Patterning a surface withcarbohydrate microarrays can allow investigation of carbohydrateinteractions with viruses, enzymes, cells, antibodies, proteins and thelike. However, most current methods for generating carbohydratemicroarrays involve either a noncovalent immobilization that becomesless stable as the molecular weight of the carbohydrate decreases, orsynthetic methods in which each carbohydrate to be spotted must first bechemically modified.

Accordingly, improved control of surface properties is currently neededto improve various applications, such as sensors, coatings, adhesives,resist layers, lubricating surfaces, microelectronics, etc., and toenable new applications.

SUMMARY OF THE INVENTION

In some aspects, the invention provides photoactive compounds of formula(I):

wherein each of the rings A-D can independently be substituted with oneor more R₁ groups and n can be any integer from 1 to 1000 (e.g., 1 to10, such as 2). In formula (I), R₁ can independently be a hydrogen, ahalogen, a hydroxyl, an aryl, an amide, a cyano, a substituted orunsubstituted straight- or branched-chain alkyl containing, for example,1 to 6 carbons, a substituted or unsubstituted alkene containing, forexample, 2 to 4 carbons, —C(O)R³, —CO₂R³, —OC(O)R³, —OR³, or —OC(O)R⁵.Each R³ can independently be a hydrogen, a substituted or unsubstitutedC₁-C₁₀ straight-chain or branched-chain alkyl, or a substituted orunsubstituted alkene. Each R⁵ can independently be a hydrogen, anunsubstituted straight- or branched-chain alkyl which contains 1-6carbons, or a straight- or branched-chain alkyl which contains 1-6carbons and is substituted by an alkyne. Y can independently be —CH₂—,—C(O)—, —OC(O)—, —C(O)O—, —C(O)NR³—, or —NR³C(O)—.

In other aspects, the invention provides photoactive compounds offormula (II):

wherein each of the rings E and F can independently be substituted withone or more R₁ groups and n can be any integer from 1 to 1000 (e.g., 1to 10, such as 2). In formula (II), R₁ can independently be a hydrogen,a halogen, a hydroxyl, an aryl, an amide, a cyano, a substituted orunsubstituted straight- or branched-chain alkyl containing, for example,1 to 6 carbons, a substituted or unsubstituted alkene containing, forexample, 2 to 4 carbons, —C(O)R³, —CO₂R³, —OC(O)R³, —OR³, or —OC(O)R⁵.Each R³ can independently be a hydrogen, a substituted or unsubstitutedC₁-C₁₀ straight-chain or branched-chain alkyl, or a substituted orunsubstituted alkene. Each R⁵ can independently be a hydrogen, anunsubstituted straight- or branched-chain alkyl which contains 1-6carbons, or a straight- or branched-chain alkyl which contains 1-6carbons and is substituted by an alkyne.

In other aspects, the invention provides photoactive compounds offormula (IV):

wherein ring I can be substituted with one or more R₁ groups and n canbe any suitable integer from 1 to 100 (e.g., 1 to 20, such as 11). Informula (IV), X can be R², —CO₂R³, —C(O)NR³R³, —SR⁴, —CN, —OR³, ahalogen, a β-diketone, a silane, a phosphate, a phosphonate, a polymer,or block copolymer. In some embodiments, X can be bound to a surface. R₁can independently be a hydrogen, a halogen, a hydroxyl, an aryl, anamide, a cyano, —R², —C(O)R³, —CO₂R³, —OC(O)R³, or —OR³. Each R² canindependently be hydrogen, a substituted or unsubstituted straight- orbranched-chain alkyl which contains 1-6 carbons, a substituted orunsubstituted alkene which contains 2-4 carbons, a substituted orunsubstituted alkyne which contains 2-4 carbons, or —OC(O)R⁵, wherein R⁵can independently be a hydrogen, an unsubstituted straight- orbranched-chain alkyl which contains 1-6 carbons, or a straight- orbranched-chain alkyl which contains 1-6 carbons and is substituted by analkyne. Each R³ can independently be a hydrogen, a substituted orunsubstituted C₁-C₁₀ straight-chain or branched-chain alkyl, or asubstituted or unsubstituted alkene. Each R⁴ can independently behydrogen, —S-pyridyl, —SR³, —SO₂R³, or —SR⁸, wherein the —SR⁸ and therest of formula (IV) can combine to form a bis-disulfide.

In one aspect, the invention provides methods for forming anon-dewetting cross-linked polymer film on a surface. Methods of theinvention can include adding to a polymer film on a surface a compoundof formula (I) or formula (II), and irradiating the compound to form across-linked polymer film. Alternatively, the method can include coatinga surface with a composition that includes a compound of formula (I) or(II), and irradiating the composition to form a cross-linked polymerfilm. The cross-linked polymer film can be resistant to dewetting fromthe surface even after heating above the glass transition temperature ormelting temperature of the polymer, or even after exposure to solvents.In some embodiments, irradiation of the polymer film may be through aphotomask, resulting in a patterned array of cross-links.

In another aspect, the invention provides methods for immobilizingmolecules on a surface. The method can include immobilizing a compoundof formula (IV) on a surface; applying a molecule to be immobilized; andirradiating the compound. A photochemical reaction between the moleculeand the compound can result in covalent links between the molecule andthe compound and the compound can be immobilized on the surface. In someembodiments, the irradiation of the compound may be through a photomask.In other embodiments, the molecule may be a carbohydrate or a polymer.In some other embodiments, the invention also provides carbohydratemicroarrays formed by the methods of the invention.

In yet another aspect, the invention provides arrays on a surface thatincludes a compound of formula (IV) immobilized on the surface and atleast one molecule covalently attached to the compound of formula (IV).In some embodiments, the molecule covalently attached to the compoundcan be a carbohydrate, a polymer, a DNA, an RNA, a protein, a peptide,and the like.

BRIEF DESCRIPTION OF THE FIGURES

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawings will be provided by the Office upon request and paymentof the necessary fee.

FIG. 1 shows a schematic of a photoactive compound of the inventionundergoing a photochemical hydrogen abstraction reaction followed byrecombination to form a covalent bond.

FIG. 2 shows a schematic of a polymer crosslinked with Compound 1 of theinvention.

FIG. 3 shows the formation of a self-assembled monolayer containingCompound 4 of the invention form on a surface.

FIG. 4 shows plausible mechanisms for crosslinking of polystyrene (PS)by a Compound 1 of the invention.

FIG. 5 shows normalized GPC traces of irradiated PS films containingvarying ratios of Compound 1 of the invention to PS.

FIG. 6A shows an optical microscope image of dewetted PS film containingCompound 1 of the invention after heating at 170° C. overnight withoutirradiation.

FIG. 6B shows an optical microscope image of dewetting resistantpolystyrene (PS) film containing Compound 1 of the invention afterirradiation and after heating at 170° C. overnight.

FIG. 6C shows an atomic force microscope (AFM) image of dewetted PS filmwithout Compound 1 of the invention after heating at 170° C. overnight.

FIG. 6D shows an AFM image of dewetting resistant polystyrene (PS) filmcontaining Compound 1 of the invention after irradiation and afterheating at 170° C. overnight.

FIGS. 7A through 7D show optical microscope images of irradiated PSfilms containing 0 mM, 1.7 mM, 7.5 mM, and 24 mM amount of Compound 1 ofthe invention.

FIG. 8A shows AFM images of PS films containing varying amounts of aCompound 1 of the invention after irradiation and heating in a vacuumoven at 170° C. overnight, where the average height and averageroughness were calculated by taking 3-5 random images and averaging theroughness and height.

FIG. 8B shows a graph of the average roughness vs. the weight percentageof Compound 1 of the invention. Values were taken from FIG. 8A.

FIG. 8C shows a graph of the average height of the film vs. the weightpercentage of photoactive compound of the invention. Values were takenfrom FIG. 8A.

FIG. 9 shows a graph of the average roughness of PS films containingCompound 1 of the invention as a function of irradiation time. The ratioof the Compound 1 to PS is 60:1. The thickness of the films withoutaddition of Compound 1 is approximately 2.5 nm. Data was obtained afterirradiation and annealing at 170° C. overnight.

FIG. 10A shows an optical microscope image of 25 nm PS film containingCompound 1 of the invention (1:3 ratio of PS:Compound 1) afterirradiation and annealing at 170° C. overnight.

FIG. 10B shows an optical microscope image of 25 nm PS film withoutCompound 1 of the invention after annealing at 170° C. overnight.

FIG. 11A shows an AFM image of a 7 nm PS film containing Compound 1 ofthe invention (1:17 ratio of PS:Compound 1) after irradiation andannealing at 170° C. overnight.

FIG. 11B shows an AFM image of 7 nm PS film without Compound 1 of theinvention after annealing at 170° C. overnight.

FIG. 12A shows an optical microscope image of a 7 nm PS film containingCompound 1 of the invention (1:18 ratio of PS: Compound 1) afterirradiation and exposure to toluene vapor.

FIG. 12B shows an optical microscope image of a 7 nm PS film withoutCompound 1 of the invention after exposure to toluene vapor.

FIG. 13A shows an optical microscope image of a 25 nm PS film containingCompound 1 of the invention (1:4 ratio of PS:Compound 1) afterirradiation and exposure to toluene vapor.

FIG. 13B shows an optical microscope image of a 25 nm PS film withoutCompound 1 of the invention after exposure to toluene vapor.

FIG. 14A shows an optical microscope image of a PS film containingCompound 1 of the invention (1:17 ratio of PS:Compound 1) on PMMA afterirradiation and annealing at 170° C. overnight.

FIG. 14B shows an optical microscope image of a PS film without Compound1 of the invention on PMMA after annealing at 170° C. overnight.

FIG. 14C shows an AFM image of a PS film containing Compound 1 of theinvention (1:17 ratio of PS:Compound 1) on PMMA after irradiation andannealing at 170° C. overnight.

FIG. 14D shows an AFM microscope image of a PS film without Compound 1of the invention after annealing at 170° C. overnight.

FIG. 15A shows an optical microscope image of an annealed PS filmcontaining Compound 1 of the invention on a 100 nm gold film afterirradiation.

FIG. 15B shows an optical microscope image of an annealed PS filmwithout a photoactive compound of the invention on a 100 nm gold filmafter irradiation.

FIG. 15C shows an optical microscope image of an annealed PS filmcontaining Compound 1 of the invention on a 100 nm gold film withoutirradiation.

FIG. 16 shows dewetting patterns formed by irradiating a PS filmcontaining Compound 1 of the invention through a photomask, where thedewetting occurs in the masked regions.

FIG. 17 show an optical microscope image of a PS film containingCompound 1 of the invention irradiated through a photomask followed byannealing above the glass transition temperature, where localizeddewetting within the pattern occurs.

FIG. 18 shows an optical microscope image demonstrating that varyingwidth of the uncrosslinked portions of the film affecting the dewettingbehavior.

FIG. 19 shows a graph of the height of the channel wall as a function ofthe channel width.

FIG. 20 shows an optical microscope image demonstrating that varying thewidth of the uncrosslinked portions of the film affects the alignment ofdroplets within the channel.

FIG. 21A shows an optical microscope image of the entire pattern of a 7nm film after irradiation and annealing.

FIG. 21B shows an optical microscope image of the pattern correspondingto the outer rim portion of the photomask for a 7 nm film afterirradiation and annealing.

FIG. 21C shows an optical microscope image of the pattern correspondingto the inner bar portion of the photomask for a 7 nm film afterirradiation and annealing.

FIG. 22 shows an AFM image of the edge of a pattern in a 7 nm film afterirradiation and annealing.

FIG. 23 shows a UV/vis spectra of a photoactive compound in ethanol(dashed line) and a self-assembled monolayer of Compound 4 (SAM 4) on asurface (straight line).

FIG. 24 shows a fluorescence spectra of 2000 kDA FITC-conjugatedα(1,6)dextran films under three conditions; irradiated SAM 4 (dashedline), unirradiated SAM 4 (dotted line), and underivatized silicon(straight line). Each spectrum was obtained after washing the surfacesfor twelve hours in water.

FIG. 25 shows a schematic illustration for direct chemical patterning ofa surface with carbohydrates using a photolithographic technique.

FIGS. 26A and 26B show water condensation experiments after patterning asurface with immobilized carbohydrates, where water is attracted to thehydrophilic carbohydrate coated regions.

FIGS. 27A and 27B show breath condensation experiments after patterninga surface with immobilized sucrose (FIG. 27A) and glucose (FIG. 27B).

FIG. 28A shows a self-assembled mixed monolayer (SAM 4A or 4B) of theinvention.

FIG. 29A shows a comparison of fluorescence emitted from a microarraycontaining spotted carbohydrates attached to SAM 4A and nitrocellulosecoated surfaces (FAST) without further treatment.

FIG. 29B shows a comparison of fluorescence emitted from a microarraycontaining spotted carbohydrates attached to SAM 4A and nitrocellulosecoated surfaces (FAST) after depositing a specific anti-carbohydratemonoclonal antibody.

FIG. 29C shows epitope-display of immobilized mono- and oligosaccharideson SAM 4A and FAST surfaces.

FIG. 30 shows an AFM image of SAM 4B on a substrate.

FIGS. 31A and 31B show a comparison of fluorescence emitted from amicroarray containing spotted carbohydrates attached to SAM 4B andnitrocellulose coated surfaces (FAST) after depositing a IgGanti-carbohydrate monoclonal antibody.

FIGS. 32A through 32C show OM images of polyvinyl alcohol (PVA),poly(tert-butyl acrylate) (PTBA), and PS immobilized on a surface.

FIG. 33 shows a plot of the thickness of PVA immobilized on a surface asa function of irradiation time after the hot water treatment

FIG. 34 shows OM image of selective electroless deposition of nickel onPAA immobilized surfaces.

DETAILED DESCRIPTION OF THE INVENTION

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to specific embodiments. It willnevertheless be understood that no limitation of the scope of theinvention is thereby intended. Alteration and further modifications ofthe invention, and further applications of the principles of theinvention as illustrated herein, as would normally occur to one skilledin the art to which the invention relates, are also within the scope ofthe invention.

Definitions

At the outset, certain terms described in this application are definedbelow.

The term “alkyl” as used herein refers to a substituted or unsubstitutedaliphatic hydrocarbon chain and includes, but is not limited to,straight and branched chains containing from 1 to 12 carbon atoms, or insome instances, from 1 to 6 carbon atoms, unless explicitly specifiedotherwise. For example, methyl, ethyl, propyl, isopropyl, butyl, i-butyland t-butyl are encompassed by the term “alkyl.” Specifically includedwithin the definition of “alkyl” are those aliphatic hydrocarbon chainsthat are optionally substituted.

The term “amide” refers to (—CONR⁹R¹⁰), wherein R⁹ and R¹⁰ areindependently hydrogen or alkyl.

The term “aryl” as used herein refers to an aromatic hydrocarbon orheterocycle. The aromatic hydrocarbon or heterocycle can contain from 3to 10 atoms in certain embodiments. For example, an aromatic hydrocarbonencompasses phenyl or naphthyl, and an aromatic heterocycle encompassespyridyl, pyrrole, thiophene, furan, diazoles, thiazoles, oxazoles, andimidazoles.

The term “carbonyl” refers to —C(O)—.

The term “β-diketone” refers to —COCH₂C(O)R⁷ wherein R⁷ is alkyl.

The term “ether” refers to —OR⁶, wherein R⁶ is a straight- orbranched-chain alkyl containing from 1 to 6 carbons or a substituted orunsubstituted aryl.

The term “ester” refers to —C(O)OR⁷ wherein R⁷ is alkyl.

The term “halogen” refers to bromine, chlorine, fluorine, and iodine.

The term “phosphate” refers to —PO₄H_(m) and its salts, wherein m is0-3, having a charge of 0, −1, or −2.

The term “phosphonate” refers to —P(OR³)₃, where R³ can independently bea hydrogen, a substituted or unsubstituted C₁-C₁₀ straight-chain orbranched-chain alkyl, or a substituted or unsubstituted alkene.

The term “silane” refers to a group comprising silicon to which at leastone hydrolyzable group is bonded, such as —Si(OCH₃)₃, —Si(OCH₂CH₃)₃,—Si(Cl)₃, -silylimidazoles, -silylamines, and the like.

The term “carbohydrate” refers to a natural or synthetic monosaccharide,oligosaccharide, polysaccharide, or a glycoside thereof.

The term “glycoside” refers to a —O—, —N—,or —S— glycoside.

The term “oligosaccharide” refers to 1-20 monosaccharides covalentlybonded together forming linear or branched structures, or structureswhich are a combination of both. Such structures include natural andsynthetic disaccharides and branched- or straight-chain tri-, tetra-,penta-, hexa-, hepta-, octa-, nona-, and decasaccharides.

The term “mixed monolayer” refers to a monolayer or a multilayercontaining at least two different types of molecules, such asphthalimides and amines.

The term “SAM” refers to a self-assembled monolayer.

Compounds of the Invention

Certain embodiments of the invention are directed to photoactivecompounds that are capable of forming covalent bonds with nearbymolecules after irradiation. In some embodiments, the invention providesphotoactive compounds that may or may not be surface bound and that arecapable of linking two molecules, such as polymers or small molecules.

In one or more aspects, the invention provides photoactive compounds offormula (I):

wherein each of the rings A-D can independently be substituted with oneor more R₁ groups and n can be any integer from 1 to 1000 (e.g., 1 to10, such as 2). In formula (I), R₁ can independently be a hydrogen, ahalogen, a hydroxyl, an aryl, an amide, a cyano, a substituted orunsubstituted straight- or branched-chain alkyl containing, for example,1 to 6 carbons, a substituted or unsubstituted alkene containing, forexample, 2 to 4 carbons, —C(O)R³, —CO₂R³, —OC(O)R³, —OR³, or —OC(O)R⁵.Each R³ can independently be a hydrogen, a substituted or unsubstitutedC₁-C₁₀ straight-chain or branched-chain alkyl, or a substituted orunsubstituted alkene. Each R⁵ can independently be a hydrogen, anunsubstituted straight- or branched-chain alkyl which contains 1-6carbons, or a straight- or branched-chain alkyl which contains 1-6carbons and is substituted by an alkyne. Y can independently be —CH₂—,—C(O)—, —OC(O)—, —C(O)O—, —C(O)NR³—, or —NR³C(O)—. In one embodiment,one or more R₁ groups are at the meta and/or para positions of each ofthe rings A-D. Examples of compounds of formula (I) can include Compound1 shown below and derivatives thereof:

In other aspects, the invention provides photoactive compounds offormula (II):

wherein each of the rings E and F can independently be substituted withone or more R₁ groups and n can be any integer from 1 to 1000 (e.g., 1to 10, such as 2). In formula (II), R₁ can independently be a hydrogen,a halogen, a hydroxyl, an aryl, an amide, a cyano, a substituted orunsubstituted straight- or branched-chain alkyl containing, for example,1 to 6 carbons, a substituted or unsubstituted alkene containing, forexample, 2 to 4 carbons, —C(O)R³, —CO₂R³, —OC(O)R³, —OR³, or —OC(O)R⁵.Each R³ can independently be a hydrogen, a substituted or unsubstitutedC₁-C₁₀ straight-chain or branched-chain alkyl, or a substituted orunsubstituted alkene. Each R⁵ can independently be a hydrogen, anunsubstituted straight- or branched-chain alkyl which contains 1-6carbons, or a straight- or branched-chain alkyl which contains 1-6carbons and is substituted by an alkyne. Examples of compounds offormula (II) can include Compound 2 shown below and derivatives thereof:

In some other aspects, the invention provides photoactive compounds offormula (III):

wherein each of the rings G and H can independently be substituted withone or more R₁ groups and n can be any suitable integer from 1 to 1000(e.g., 1 to 100, 1 to 20, such as 11). In formula (III), X can be R²,—CO₂R³, —C(O)NR³R³, —SR⁴, —CN, —OR³, a halogen, a β-diketone, a silane,a phosphate, a phosphonate, a polymer, or block copolymer. In someembodiments, X can be bound to a surface. R₁ can independently be ahydrogen, a halogen, a hydroxyl, an aryl, an amide, a cyano, —R²,—C(O)R³, —CO₂R³, —OC(O)R³, or —OR³. Each R² can independently behydrogen, a substituted or unsubstituted straight- or branched-chainalkyl which contains 1-6 carbons, a substituted or unsubstituted alkenewhich contains 2-4 carbons, a substituted or unsubstituted alkyne whichcontains 2-4 carbons, or —OC(O)R⁵, wherein R⁵ can independently be ahydrogen, an unsubstituted straight- or branched-chain alkyl whichcontains 1-6 carbons, or a straight- or branched-chain alkyl whichcontains 1-6 carbons and is substituted by an alkyne. Each R³ canindependently be a hydrogen, a substituted or unsubstituted C₁-C₁₀straight-chain or branched-chain alkyl, or a substituted orunsubstituted alkene. Each R⁴ can independently be a hydrogen,—S-pyridyl, —SR³, —SO₂R³, or —SR⁸, wherein the —SR⁸ and the rest offormula (III) can combine to form a bis-disulfide. Y can independentlybe —CH₂—, —C(O)—, —OC(O)—, —C(O)O—, —C(O)NR³—, or —NR³C(O)—. Examples ofa compound of formula (III) can include Compound 3 shown below andderivatives thereof:

In other aspects, the invention provides photoactive compounds offormula (IV):

wherein ring I can be substituted with one or more R₁ groups and n canbe any suitable integer from 1 to 1000 (e.g., 1 to 100,1 to 20, such as11). In formula (IV), X can be R², —CO₂R³, —C(O)NR³R³, —SR⁴, —CN, —OR³,a halogen, a β-diketone, a silane, a phosphate, a phosphonate, apolymer, or block copolymer. In some embodiments, X can be bound to asurface. R₁ can independently be a hydrogen, a halogen, a hydroxyl, anaryl, an amide, a cyano, —R², —C(O)R³, —CO₂R³, —OC(O)R³, or —OR³. EachR² can independently be hydrogen, a substituted or unsubstitutedstraight- or branched-chain alkyl which contains 1-6 carbons, asubstituted or unsubstituted alkene which contains 2-4 carbons, asubstituted or unsubstituted alkyne which contains 2-4 carbons, or—OC(O)R⁵, wherein R⁵ can independently be a hydrogen, an unsubstitutedstraight- or branched-chain alkyl which contains 1-6 carbons, or astraight- or branched-chain alkyl which contains 1-6 carbons and issubstituted by an alkyne. Each R³ can independently be a hydrogen, asubstituted or unsubstituted C₁-C₁₀ straight-chain or branched-chainalkyl, or a substituted or unsubstituted alkene. Each R⁴ canindependently be a hydrogen, —S-pyridyl, —SR³, —SO₂R³, or —SR⁸, whereinthe —SR⁸ and the rest of formula (IV) can combine to form abis-disulfide. Examples of a compound of formula (IV) can includeCompound 4 shown below and derivatives thereof:

In some embodiments, the photoactive compounds of the invention caninclude compounds that can form radicals that lead to the formation ofcovalent bonds. For example, exposure to UV light can allow thephotoactive compound to undergo photochemical hydrogen abstractionreactions (e.g., abstracting a hydrogen atom from a nearby molecule).The resulting radicals can then recombine, forming a covalent bond. Insome embodiments, the photoactive compounds of the invention can includecompounds that can form radicals near a carbonyl group. Moreover, thephotoactive compounds of the invention can include aromatic carbonylfunctional groups that can react with hydrogen atom donors (e.g., C—Hgroups, Si—H groups, S—H groups, and the like) upon absorption of aphoto to form covalent bonds. As an example, FIG. 1 schematicallydemonstrates the abstraction of hydrogen from a phthalimide derivative,undergoing a transition to produce an excited n-π* state. As shown, aradical can be generated near a carbonyl group, which then can form anew covalent bond by reacting with nearby molecules. Other examples ofphotoactive compounds of the invention can include mono-benzophenone,bis-benzophenone, mono-phthalimide, bis-phthalimide, or derivativecompounds thereof.

Alternatively, the photoactive compounds of the invention can abstractelectrons from molecules that have suitable electron donating groups,such as amines and sulfides. Electron transfer to the photoactivecompound can be followed by proton transfer and can result in covalentbond formation between the photoactive compound and the molecule havinga suitable electron donating group in a manner similar to hydrogenabstraction described above.

The specific choice of photoactive compound for use in the inventionwill depend on characteristics of the desired application. For example,self quenching ability, quenching by a particular polymer, miscibilityin various polymers, and whether there are chromophores in thesurrounding that are affected by various wavelengths of light can all befactors to consider in choosing the desired photoactive compounds of theinvention.

The invention also provides compounds of Formula (V):

wherein X can be —R², —CO₂R³, —C(O)NR³R³, —SR⁴, —CN, —OR³, a halogen, aβ-diketone, a silane, a phosphate, a phosphonate, a polymer, or blockcopolymer; Z can be —NR³R³, —OH, —SH, —C(O)NR³R³, —CO₂R³, a carboxylate,an ammonium, or a salt thereof; and n can be an integer from 1 to 1000,such as 1 to 100, 1 to 30, 1 to 20, 1 to 15, 1 to 10, 5 to 20, 5 to 15,5 to 10, or 15 to 30, or n is 8, 9, 10, 11, 12, or 13. Each R² canindependently be hydrogen, a substituted or unsubstituted straight- orbranched-chain alkyl which contains 1-6 carbons, a substituted orunsubstituted alkene which contains 2-4 carbons, a substituted orunsubstituted alkyne which contains 2-4 carbons, or —OC(O)R⁵, wherein R⁵can independently be a hydrogen, an unsubstituted straight- orbranched-chain alkyl which contains 1-6 carbons, or a straight- orbranched-chain alkyl which contains 1-6 carbons and is substituted by analkyne. Each R³ can independently be a hydrogen, a substituted orunsubstituted C₁-C₁₀ straight-chain or branched-chain alkyl, or asubstituted or unsubstituted alkene. Each R⁴ can independently be ahydrogen, —S-pyridyl, —SR³, —SO₂R³, or SR⁸, wherein the —SR⁸ and therest of formula (V) can combine to form a bis-disulfide. In oneembodiment, Z can be a polar group or a group that has a charge, such asa positive or negative charge. Examples of a compound of formula (V) caninclude Compound 5 shown below and derivatives thereof:

In some embodiments, compounds of Formula (III), (IV), and (V) can beimmobilized on a surface as a mixture containing at least two of thecompounds. For example, the compounds of Formula (V) can be mixedtogether with a compound of Formula (III) or (IV), or both, prior to orconcurrently with addition to the surface. The compound of Formula (V)may be able to improve the biomolecular compatibility and/or bindingaffinity for molecules to be immobilized, such as a carbohydrate, tosurfaces having the compounds of Formula (III) and/or (IV).

In some embodiments, the ratio of compound of Formula (V) to compound ofFormula (III) and/or (IV) may be from about 100:1 to about 1:1. Forexample, the ratio of compound of Formula (V) to compound of Formula(III) and/or (IV) may be from about 100:1, 80:1, 60:1, 50:1, 30:1, 20:1,10:1, 5:1, 2:1, and the like to about 1:1.

Therefore, the compounds of the invention have a number of significantadvantages over those of the conventional art. For example, a protectinggroup is not needed which can facilitate in the synthesis of thecompounds. Moreover, additional reagents are not needed to react withthe compounds as the radicals that form upon irradiation can readilyform covalent bonds with nearby molecules.

It should be noted that other photoactive compounds having a similarstructure to that shown for compounds of Formula (I) through (IV)described above are within the scope of the invention. For example, thephthalimide or benzophenone portion of compounds of Formula (I) through(IV) can be replaced with acetone, xanthone, and other aromatichydrocarbons having carbonyl groups. For example, compounds of Formula(VI) are within the scope of the invention,

wherein each of the rings A-D can independently be substituted with oneor more R₁ groups and n can be any integer from 1 to 1000 (e.g., 1 to10, such as 2). In formula (VI), R₁ can independently be a hydrogen, ahalogen, a hydroxyl, an aryl, an amide, a cyano, a substituted orunsubstituted straight- or branched-chain alkyl containing, for example,1 to 6 carbons, a substituted or unsubstituted alkene containing, forexample, 2 to 4 carbons, —C(O)R³, —CO₂R³, —OC(O)R³, —OR³, or —OC(O)R⁵.Each R³ can independently be a hydrogen, a substituted or unsubstitutedC₁-C₁₀ straight-chain or branched-chain alkyl, or a substituted orunsubstituted alkene. Each R⁵ can independently be a hydrogen, anunsubstituted straight- or branched-chain alkyl which contains 1-6carbons, or a straight- or branched-chain alkyl which contains 1-6carbons and is substituted by an alkyne. Y can independently be —CH₂—,—C(O)—, —OC(O)—, —C(O)O—, —C(O)NR³—, or —NR³C(O)—. In one embodiment,one or more R₁ groups can be at the meta and/or para positions of eachof the rings A-D. Other exemplary compounds described above will bereadily apparent to one of ordinary skill in the art.

Controlling Surface Properties of Material

The invention relates to methods for controlling surface properties ofmaterials. In certain embodiments, methods for controlling the dewettingproperties of layers on surfaces are described. In other embodiments,methods for providing a desired architecture on a surface are providedby controlling the dewetting properties of layers on surfaces. In yetother embodiments, methods for controlling the affinity for certainmaterials on the surface are provided.

In the following embodiments, compounds of formula (I), compounds offormula (II), compounds of formula (III), and/or compounds of formula(IV) can be utilized as a photoactive compound. For example,mono-benzophenone, bis-benzophenone, mono-phthalimide, bis-phthalimide,or derivative compounds thereof can be utilized. The amount of compoundadded will depend on the desired amount for each application, as can bereadily determined by one skilled in the art. For example, thephotoactive compound can be utilized as a 1% solution.

In certain embodiments, irradiation can be carried out with ultravioletlight. In some embodiments, light of wavelengths from 290-350 nm, (e.g.,290-300 nm and/or 330-350 nm) can be used in the invention. In oneembodiment, the polymer film can be irradiated for a period of timesuitable to form the desired amount of cross-links. For example, thepolymer film can be irradiated for about an hour. The extent of reactionmay be monitored with techniques known to the skilled artisan, such asoptical microscopy and atomic force microscopy to look at the degree ofdewetting, and infrared spectroscopy to look at the disappearance of thecarbonyl peak.

The surface can be the surface of an inorganic material, an organicmaterial, a polymer, and the like. For example, the surface can be thesurface of silicon, titania, glass, gold, polycarbonate, polystyrene,poly(vinyl alcohol), poly(tert-butyl acrylate), poly(methylmethacrylate), paper, fingernail, and the like.

In certain embodiments, the surface can be the surface of a device, suchas a chip, an optical lens, a plate, a sensor, a biomedical device, acircuit, a substrate for electroplating, or a combination thereof.

Controlling Dewetting Properties of Polymers

In certain embodiments, the invention relates to methods for stabilizinglayers from dewetting from a surface. Methods of the invention caninclude (1) adding a photoactive compound (e.g. Compound 1 shown in FIG.2) to a polymer 201 on a surface, where the photoactive compound iscapable of forming covalent bonds with nearby molecules uponirradiation, and (2) irradiating the compound to form a cross-linkedpolymer. The resulting cross-linked polymer, schematically shown in FIG.2, can be resistant to dewetting from the surface. For example, thecross-linked polymer can be resistant to dewetting even after heatingabove the glass transition temperature or melting temperature of thepolymer and/or after exposure to one or more solvents.

In yet other embodiments, methods of the invention can include (1)coating a surface with a composition that include a polymer and aphotoactive compound capable of forming covalent bonds with nearbymolecules after irradiation, and (2) irradiating the composition to forma cross-linked polymer.

The cross-linked polymer described above can be formed as a coating on asurface, and at various thicknesses. For example, the cross-linkedpolymer can form a coating with a thickness of less than 5 nm, 10 nm, 20nm, 50 nm, 100 nm, 500 nm, 1 micron, 10 micron, 50 micron, 100 micron,200 micron, 300 micron, 500 micron and the like. If a monolayer ofpolymer is formed on the surface, the thickness can depend on themolecular weight of the polymer. In some embodiments, the polymer may beapplied to the surface by spin coating, spray coating, or any otherconventional techniques known in the art to obtain a uniform coating.

In some embodiments, the photoactive compound can further include adesired functional group. Some examples of desired functional groupinclude functional groups that have specific affinity to othermolecules, such as peptides or small molecules. In other embodiments,one or more additional compounds that are capable of providing a desiredfunctionality can be added to a polymer on a surface. Some examples ofone or more additional compounds can include one or more of a peptide,growth factor, antibody, small molecule drug, carbohydrate, lipid,antibiotic, antimicrobial, and the like. In some embodiments, thedesired functionality may be at least some resistance to antigens, nerveagents, and the like.

Any polymer can be used in the invention. Some exemplary polymers caninclude polymers that contain a tertiary hydrogen and electron donatingor withdrawing groups that can form resonance structures with theresulting radical after hydrogen abstraction occurs on the polymerchain, such as polystyrenes, polyethers, polyesters, polyamides,polyvinyls, polysaccharides, and the like.

The invention also provides methods for forming a non-dewetting,patterned array of cross-linked polymer. In certain embodiments, arobotic spotter can be utilized to pattern areas containing aphotoactive compound and polymer, and the patterned array can beirradiated. Alternatively, a mask containing the desired pattern orimage can be placed over a surface coated with a photoactive compoundand polymer, and the coating can be irradiated though the mask. Othersuitable methods to form a patterned array of cross-linked polymer willbe readily apparent to one of ordinary skill in the art. The patternedarray of cross-linked polymer can become resistant to dewetting.

The cross-linked polymer films of the invention have applications inthin film device fabrication, particularly in microelectronics, sensors,and coating compositions. For example, a polymer surface applied to asurface acoustic wave sensor can serve as an artificial nose or sniffersystem. Generally, thin polymer films are coated onto quartz, and anaromatic ketone group on the surface reacts in the presence of light,where adsorption causes a change in the wave sensor. The invention canprovide polymer films that can be utilized to form stable surfaces thatthat normally would not be stable and improve the performance of thesedevices.

Other examples include use of the polymer films as adhesives, such asself-adhesives, hot-melt adhesives, or as UV-curable binding agents incoating compositions, such as protective materials for coating mineralsurfaces or as paints. The methods of the invention are particularlysuitable for the production of coatings and protective films, such ascoatings for clothing, cosmetics, and personal care products.

The cross-linked polymer film of the invention can also be applied as aremovable layer in many applications. For example, a polymer can beapplied to the skin of a burn patient, cross-linked to form a protectivesurface layer, and the cross-linked polymer can be peeled off later. Across-linked polymer of the invention can also be used as a toughsurface layer for inorganic substrates, such as hydrogels or monolayers.

The addition of a desired functionality to the non-dewettingcross-linked polymer film can be particularly desirable for some thinfilm applications. For example, the methods of the invention can besuitable for linking biological molecules such as peptides, growthfactors, antibodies, small molecule drugs, carbohydrates, lipids,antibiotics and antimicrobials to non-dewetting polymer films. For woundhealing applications, polymer films can be fabricated to deliverbiological molecules such as growth factors or antigen-resistant drugsto the site of injury.

The methods of the invention are also applicable to the development ofprotective coatings for use against biological weapons. For example, adesired functionality such as nerve agent or antigen resistance can beprovided to a polymer, and the polymer applied as a protective coatingto clothing worn by military personnel.

Forming Three-Dimensional Structures on Surfaces

The invention also provides methods for forming three-dimensionalstructural features. Methods of the invention can include (1) adding aphotoactive compound to a polymer on a surface, where the photoactivecompound is capable of forming covalent bonds with nearby molecules uponirradiation, (2) placing a mask which contains a desired pattern, (3)irradiating the photoactive compound through the mask to form a patternof cross-linked and uncrosslinked polymer, and (4) heating the patternto a temperature that is near or above the glass transition temperatureor the melting temperature of the polymer. Upon heating the surface, atleast some of the uncrosslinked polymer can migrate toward the interfacebetween the crosslinked and uncrosslinked regions to form a verticalstructure.

In other embodiments, methods of the invention can include (1) coating asurface with a composition that includes a polymer and a photoactivecompound capable of forming covalent bonds with nearby molecules afterirradiation, (2) placing a mask which contains a desired pattern, (3)irradiating the photoactive compound through the mask to form a patternof cross-linked and uncrosslinked polymer, and (4) heating the patternto a temperature that is near or above the glass transition temperatureor the melting temperature of the polymer. Upon heating the surface, atleast some of the uncrosslinked polymer can migrate toward the interfacebetween the crosslinked and uncrosslinked regions to form a verticalstructure.

In yet other embodiments, methods of the invention can include (1)coating a surface with a polymer (2) forming on the polymer a pattern ofphotoactive compound capable of forming covalent bonds with nearbymolecules after irradiation, (3) irradiating the photoactive compound toform a pattern of cross-linked and uncrosslinked polymer, and (4)heating the pattern to a temperature that is near or above the glasstransition temperature or the melting temperature of the polymer. Uponheating the pattern, at least some of the uncrosslinked polymer canmigrate toward the interface between the crosslinked and uncrosslinkedregions to form a vertical structure.

In some embodiments, the polymer may be applied to the surface by spincoating, spray coating, or any other conventional techniques known inthe art to obtain a uniform coating.

The polymer described above can be formed as a coating on a surface, andat various thicknesses. For example, the polymer may be formed as acoating with a thickness of greater than 1 nm, 5 nm, 10 nm, 20 nm, 50nm, 100 nm, 500 nm, 1 micron, 10 micron, 50 micron, 100 micron, 200micron, 300 micron, 500 micron and the like. If a monolayer of polymeris formed on the surface, the thickness can depend on the molecularweight of the polymer.

The pattern described above can be formed at various widths. Forexample, the uncrosslinked or crosslinked regions can be formed have awidth that is greater than 20 nm, 50 nm, 100 nm, 500 nm, 1 micron, 10micron, 50 micron, 100 micron, 200 micron, 300 micron, 500 micron, 1 mm,and the like.

The height of the vertical structure that builds up near the interfaceof the crosslinked and uncrosslinked regions can be dependent on thethickness of the polymer film and/or the width of the uncrosslinkedregions. Greater thickness and width of the uncrosslinked regions maylead to greater height of the vertical structure near the interface. Theheight of the material that builds up near the interface can be greaterthan 5 nm, 10 nm, 20 nm, 50 nm, 100 nm, 200 nm, 300 nm, 500 nm, 1000 nm,and the like.

In some embodiments, the photoactive compound can further include adesired functional group. Some examples of desired functional group caninclude functional groups that have specific affinity to othermolecules, such as peptides or small molecules. In other embodiments, asecond compound that is capable of providing a desired functionality canbe added to a polymer on a surface. Some examples of the second compoundinclude one or more of a peptide, growth factor, antibody, smallmolecule drug, carbohydrate, lipid, antibiotic, antimicrobial, and thelike. In some embodiments, the desired functionality may be at leastsome resistance to antigens, nerve agents, and the like.

Any suitable polymer can be used in the invention. Some exemplarypolymers can include polymers that contain a tertiary hydrogen andelectron donating or withdrawing groups that can form resonancestructures with the resulting radical after hydrogen abstraction occurson the polymer chain, such as polystyrenes, polyethers, polyesters,polyamides, polyvinyls, polysaccharides, and the like.

The patterned three-dimensional structures can be utilized in a numberof different applications, such as for microreactors carrying outmicroscopic amounts of reaction near the surface. The patternedthree-dimensional structures may be utilized as assays to determinewhich reactions are successful by placing suitable markers afterreaction. For example, to test for successful synthesis of a particularcarbohydrate, various different reagents can be utilized in eachmicroreactor. After the surface has been subjected to a suitablereaction condition, a marker can be deposited into the microreactors,where the marker fluoresces only when it binds to the carbohydrates thatform after a completed reaction. The detection of the fluorescencesignal in various microreactors can be utilized to determine whichreagents are suitable for a successful reaction.

Immobilizing Molecules on a Surface

Other embodiments of the invention also relate to methods forimmobilizing molecules on a surface. Methods of the invention caninclude (1) immobilizing on a surface a photoactive compound capable offorming covalent bonds with nearby molecules after irradiation; (2)applying a molecule to the photoactive compound; and (3) irradiating thephotoactive compound, wherein a photochemical reaction between thephotoactive compound and the molecule results in covalent links betweenthe molecule and the photoactive compound to immobilize the moleculenear the surface. In certain embodiments, the photoactive compound canbe immobilized on the surface as a self-assembled monolayer (see FIG.3). In other embodiments, the photoactive compound can be immobilized onthe surface as a multilayer.

In other some embodiments, methods of the invention can include (1)immobilizing on a surface a composition that includes a photoactivecompound capable of forming covalent bonds with nearby molecules afterirradiation and a second compound that can increase the affinity ofdesired molecules to the composition; (2) applying a molecule to thecomposition; and (3) irradiating the composition, wherein aphotochemical reaction between the photoactive compound and the moleculeresults in covalent links between the molecule and the photoactivecompound to immobilize the molecule near the surface. In certainembodiments, the composition can be immobilized on the surface as aself-assembled monolayer. In other embodiments, the photoactive compoundcan be immobilized on the surface as a multilayer.

In some embodiments, the molecule that forms covalent links with thephotoactive compound can be a carbohydrate.

The invention also provides methods for immobilizing a patterned arrayof molecules on a surface. A mask containing the desired pattern orimage can be placed over the coated surface and irradiated through themask. Alternatively, a robotic spotter can be utilized to pattern areascontaining a photoactive compound and a molecule, and the patternedarray can be irradiated. Other suitable methods to form a patternedarray of immobilized carbohydrates will be readily apparent to one ofordinary skill in the art.

The photoactive compound and/or the immobilized molecule can be formedas a coating on a surface, and at various thicknesses. For example, themolecule may form a coating with a thickness of less than 1 nm, 2 nm, 5nm, 10 nm, 20 nm, 50 nm, 100 nm and the like. For example, if amonolayer of immobilized molecule is formed on the surface, thethickness can depend on the molecular weight of the molecule. In someembodiments, the molecule may be applied to the surface by spin coating,spray coating, or any other conventional techniques known in the art toobtain a uniform coating.

In some embodiments, the photoactive compound can further include afunctional group capable of being immobilized on a surface. Someexamples of functional group capable of being immobilized on a surfaceinclude a carboxylic acid, thiol, β-diketone, silane, phosphate,phosphonate, alkane, alkene, or alkyne, polymer, block co-polymer, andthe like. In some other embodiments, the photoactive compound can beincorporated into polymers and/or hydrogels to modify themolecule-surface interfacial tension or to modify steric constraintsthat may make the photoactive portion of the molecule inaccessible.

Any suitable molecules can be utilized. Carbohydrates, polymers, lipids,proteins, and the like can be utilized. For example, carbohydrates, suchas monosaccharides, disaccharides, trisaccharides, tetrasaccharides,oligosaccharides, polysaccharides, glycosides thereof, and the like, canbe utilized in the invention. In some embodiments, the carbohydrate canbe a simple carbohydrate, such as glucose or sucrose. In otherembodiments, a 2000 kDA dextran can be utilized. In some otherembodiments, the carbohydrates can be underivatized carbohydrates,without chemical modification. As another example, suitable polymers caninclude polyacrylic acid, polystyrene, polyvinyl alcohol, and the like.Other exemplary molecules that can be immobilized on a surface will bereadily apparent to one of ordinary skill in the art.

The invention does not require the chemical modification of eachmolecule prior to deposition and it is not dependent on the molecularweight of the deposited molecule. Moreover, the invention can utilizebonds, such as C—H bonds, S—H bonds, Si—H bonds, and the like, which ispresent in many molecules (e.g., C—H bonds are readily found incarbohydrates). Moreover, the invention requires no reagents andgenerates no byproducts.

The invention has applications in a wide number of applications. Forexample, the invention can be utilized in tissue engineering, sensorfabrication, glycome sequencing, and in microarray construction forhigh-throughput characterization of carbohydrate enzyme activity andcarbohydrate interactions with cells, antibodies, proteins andmicroorganisms.

Moreover, the surfaces may be used as biological sensors for identifyingbiological warfare agents. The invention also provides a platform forscreening antibody activity towards various viruses, photopatterning anykind of polymer, biological or synthetic, that contains a C—H bond, andglycomic and proteomic studies aimed at the discovery of new drugs andthe understanding of cellular processes.

The invention can also be utilized as immobilized coatings that impartdesired functionality to a surface. For example, hydrophilic moleculescan be immobilized on the surface of an optically transparent substrateto provide an anti-fogging substrate. An another example, hydrophobicmolecules can be immobilized on the surface of a substrate to provide asurface that strongly repels water (e.g., to coat automobile windshieldto repel rain water).

In some embodiments, arrays having the photoactive compounds of theinvention immobilized on a surface can be utilized to covalently attachnumerous molecules, such as DNA, RNA, proteins, polymers, carbohydrates,and the like to the photoactive compounds for applications describedherein.

In addition, a patterned array of molecules can be utilized as atemplate for carrying out further reactions selectively in desired areasof the patterned surface.

Depositing Metals on a Surface

Other embodiments of the invention also relate to methods for depositingmetals on a surface. Methods of the invention can include (1)immobilizing on a surface a photoactive compound capable of formingcovalent bonds with nearby molecules after irradiation; (2) applying amolecule to the photoactive compound; (3) irradiating the photoactivecompound, wherein a photochemical reaction between the photoactivecompound and the molecule results in covalent links between themolecules and the photoactive compound to immobilize the molecule nearthe surface; (4) contacting the surface having immobilized moleculeswith a catalyst for forming a metal, where the catalyst has a selectiveaffinity for the immobilized molecules; and (5) carrying out a metalreducing reaction to deposit metal near the immobilized molecules. Incertain embodiments, the photoactive compound can be immobilized on thesurface as a self-assembled monolayer. In other embodiments, thephotoactive compound can be immobilized on the surface as a multilayer.

In some other embodiments, methods of the invention can include (1)immobilizing on a surface a composition that includes a photoactivecompound capable of forming covalent bonds with nearby molecules afterirradiation and a second compound that can increase the affinity ofdesired molecules to the composition; (2) applying a molecule to thecomposition; (3) irradiating the composition, wherein a photochemicalreaction between the photoactive compound and the molecule results incovalent links between the molecule and the photoactive compound toimmobilize the molecule near the surface; (4) contacting the surfacehaving immobilized molecules with a catalyst for forming a metal, wherethe catalyst has a selective affinity for the immobilized molecules; and(5) carrying out a metal reducing reaction to deposit metal near theimmobilized molecules. In certain embodiments, the photoactive compoundcan be immobilized on the surface as a self-assembled monolayer. Inother embodiments, the photoactive compound can be immobilized on thesurface as a multilayer.

In some embodiments, a mask containing the desired pattern or image canbe placed over the surface and irradiated though the mask.Alternatively, a robotic spotter can be utilized to pattern areascontaining a photoactive compound and a molecule, and the patternedarray can be irradiated. Other suitable methods to form a patternedarray of immobilized carbohydrates will be readily apparent to one ofordinary skill in the art.

The photoactive compound and/or the immobilized molecule can be formedas a coating on a surface, and at various thicknesses. For example, themolecule may form a coating with a thickness of less than 1 nm, 2 nm, 5nm, 10 nm, 20 nm, 50 nm, 100 nm and the like. For example, if amonolayer of immobilized molecule is formed on the surface, thethickness can depend on the molecular weight of the molecule. In someembodiments, the molecule may be applied to the surface by spin coating,spray coating, or any other conventional techniques known in the art toobtain a uniform coating.

In some embodiments, the photoactive compound can further include afunctional group capable of being immobilized on a surface. Someexamples of functional group capable of being immobilized on a surfaceinclude a carboxylic acid, thiol, β-diketone, silane, phosphate,phosphonate, alkane, alkene, or alkyne, polymer, block co-polymer, andthe like. In some other embodiments, the photoactive compound can beincorporated into polymers and/or hydrogels to modify thecarbohydrate-surface interfacial tension or to modify steric constraintsthat may make the photoactive portion of the molecule inaccessible.

Any suitable molecules can be utilized. Carbohydrates, polymers, lipids,proteins, and the like can be utilized. Suitable polymers can includepolyacrylic acid, polystyrene, polyvinyl alcohol, and the like. Otherexemplary molecules than can be immobilized on a surface will be readilyapparent to one of ordinary skill in the art.

Any suitable metals can be deposited on the surface with the use ofappropriate catalysts. For example, nickel, copper, gold, silver,titanium, aluminum, silicon, and the like can be deposited. Theinvention has significant advantages over conventional techniques, suchas electroplating, as expensive and potentially dangerous reactionconditions can be avoided.

Although the invention was described in reference to deposition ofmetals, other non-metals, such as insulator, semiconductors, organicmolecules, polymers, and the like can be deposited, as will be readilyapparent to one of ordinary skill in the art.

EXAMPLES

The invention will be further described with reference to the followingexamples; however, it is to be understood that the invention is notlimited to such examples. Rather, in view of the present disclosure thatdescribes the current best mode for practicing the invention, manymodifications and variations would present themselves to those of skillin the art without departing from the scope and spirit of thisinvention. All changes, modifications, and variations coming within themeaning and range of equivalency of the claims are to be consideredwithin their scope.

Example 1 Synthesis of a Compound of Formula (I)

To a solution of 6.7 g (0.03 mol) of 3-benzoylbenzoic acid (Aldrich) in250 ml of methylene chloride and 50 ml of ether in a 500 ml three neckedround bottom flask which was equipped with a reflux condenser and sealedwith argon was added 0.4 g (0.003 mol) of 4-pyrrolidinopyridine(Aldrich), and 6.1 g (0.03 mol) of DCC (Acros). The solution was stirredfor 5 min. 0.93 g (0.015 mol) of ethylene glycol was added. The reactionmixture was stirred overnight and then refluxed for 5 hours to completethe esterification. After cooling to room temperature, theN,N-dicyclohexyl urea was removed by filtration. The filtrate was washedwith water (3×100 ml), 5% acetic acid solution (3×100 ml), water (2×100ml), and NaCl saturated water (100 ml). The solution was dried withanhydrous Na₂SO₄. After removing the solvent on a rotoevaporator, theproduct was chromatographed on silica gel with ethyl acetate/hexane(v/v=1/3). 6.5 g of Compound 1 was obtained (90% yield).

Example 2 Derivatization of Compound 1

Halogenation. Addition of a halogen with a Lewis acid allows forhalogenation of the aromatic rings in the meta positions. The halogencan then be replaced by a molecule bearing a nucleophile.

Alkylation Using an Alkene. Addition of an alkene with a Bronsted orLewis acid results in substitution in the meta positions.

Alkylation Using an Alcohol. Addition of an alcohol with a Bronsted orLewis acid results in substitution in the meta positions.

Additionally, benzophenone derivatives bearing substituents that areamenable to derivatization (methoxy, alcohol, etc.) can be used to makethe derivative compound of Compound 1.

Example 3 Synthesis of a Compound of Formula (II)

150 ml of DMF was added to a flask containing 1.056 g of potassiumphthalimides. 0.7145 g of dibromohexane was added. The solution wasstirred overnight at 20° C. 75 ml of chloroform were added to thesolution followed by 50 ml H₂O. The organic layer was separated andextracted with 50 ml of chloroform two times. The combined organiclayers were rinsed with 75 ml of H₂O four times. Chloroform was removedunder reduced pressure. A clear liquid removed. White needles ofCompound 2 precipitated from the liquid after 12 hours. The product ofwas collected by filtration and washed with ether.

Example 3 Synthesis of a Compound of Formula (IV)

9.8 mmol of 11-bromoundecanetrimethoxysilane (Gelest) was added to asolution of an equimolar amount of potassium phthalimides (Aldrich) in40 ml of anhydrous DMF (Aldrich) (see also FIG. 3). The solution wasstirred overnight at room temperature under argon. 30 ml of chloroformwere added. The solution was transferred to a separate flask containing50 ml of H₂O. The aqueous layer was separated and then extracted withtwo 20 ml portions of chloroform. The combined chloroform extract waswashed with three 20 ml portions of H₂O. The chloroform was removed byrotoevaporation to give approximately 20 ml of product (Compound 4). Thecompound was characterized by NMR and used without further purification.

Example 5 Fabrication of Dewetting-Resistant Polymer Film

Polymer films were prepared on Silicon wafers (Wafer World) byspin-coating toluene solutions containing varying amounts of polystyrene(PS) and Compound 1 (see FIG. 4). Typically, films were spun at 3000 rpmfor 1 minute. Silicon wafers were cleaned by boiling in “piranha”solution (7:3 sulfuric acid/H₂O₂) for 1 hour followed by an extensiverinse with H₂O and methanol. Surfaces were dried with a stream of argonand placed in a UV/ozone cleaner for 20 minutes prior to casting thefilm.

The films were placed in sealed glass vials and purged with argon for 10minutes. The films were irradiated for 1 hour with a RayonetPhotochemical Reactor equipped with lamps that emit at 350 nm. FIG. 4shows plausible mechanisms for the photoinduced cross-linking reaction.Irradiation is expected to produce an excited n-π* state thatintersystem crosses to the triplet. One of several deactivation pathwaysincludes hydrogen abstraction of a nearby C—H group on a PS chain (step1). Hydrogen abstraction can form radicals that can recombine to formcovalent bonds. Two potential recombination pathways can result incross-links. First, radical centers on the PS chains can recombine witheach other (step 2). This requires that the photogenerated PS radicalsare located sufficiently close to each other. This pathway may belimited in that the chain motion can be hindered by the solid-statereaction conditions used to cross-link the film. Second, the inclusionof two benzophenone chromophores can supply an additional cross-linkingpathway that circumvents the need to have two macroradical centers inclose proximity. Recombination of two benzophenone ketyl radicals at theends of a single molecule of Compound 1 with PS macroradicals results incross-links without the need for two interacting PS radicals. Theexcitation wavelength of Compound 1 occurs around 340 nm, sufficientlyseparated from the absorption band of the PS phenyl rings that fallsbelow 280 nm.

The irradiated PS films were examined by infrared (IR) spectroscopy andgel permeation chromatography (GPC). Hydrogen abstraction is expected tooccur at the aromatic ketone as schematically illustrate in FIG. 4.Examination of the corresponding peak in the IR spectrum indicateswhether this chromophore can participate in a photochemical reactionmixed within the polymer matrix. IR spectra show that the aromaticketone at 1661 cm⁻¹ decays relative to the ester groups at 1725 cm⁻¹over time (not shown). The observed decrease in the aromatic ketoneabsorbance as a function of time demonstrates that Compound 1 canundergo a photochemical reaction while confined in a polymer matrix.

To further verify that PS can be photochemically cross-linked byphotoexcitation of Compound 1 in a PS matrix, samples containingCompound 1 and PS (M_(n)=2600) were analyzed by GPC. It should be notedthat GPC can qualitatively demonstrate the occurrence of cross-linkingAnalysis of the GPC curves shown in FIG. 5 shows that the lowestmolecular weight peak, which occurs at comparable retention times in allof the samples, shifted to higher molecular weight after irradiation. Insome cases, the shift was accompanied by the growth of new peakscorresponding to higher molecular weights. The formation of highermolecular weight species suggests that irradiation of Compound 1 withinthe polymer film results in cross-linked (i.e., branched) PS chains. Itis possible that insoluble higher molecular weight networks that werenot detected using GPC were created. The decay of the aromatic carbonyland an increase in the molecular weight of the PS chains afterirradiation are consistent with the hypothesis that Compound 1photochemically cross-links the PS chains as a result of photoinduced Habstraction.

To examine the effect of crosslinking on the dewetting behavior of PS,samples having 29:1 ratio of Compound 1:PS and without any Compound 1were heated to about 170° C. (Tg is about 100° C.). FIGS. 6A and 6B showoptical microscope (OM) images of these samples (without and withCompound 1, respectively) and FIGS. 6C and 6D show atomic forcemicroscope (AFM) images (without and with Compound 1, respectively) forthese samples. As shown in FIGS. 6A and 6C, samples without any Compound1 have numerous holes. However, as shown in FIGS. 6B and 6D, samplescontaining Compound 1 have significantly reduced amount of holes,suggesting increased resistance to dewetting. It should be noted thatfor this particular sample, the AFM images were not obtained until ahole could be found, biasing the experiment toward a positive holeresult. Even with this built-in bias, the film appears to be lessdamaged than the sample without Compound 1. Moreover, the averageroughness of the film containing Compound 1 is about 0.3 nm compared tothe roughness value of 1.9 nm for the sample without Compound 1, adecrease by more than a factor of 6. These results show that irradiationof films containing Compound 1 results in cross-links that inhibit thepolymer chains from reorganizing on the surface.

Additional films were cast containing intermediate concentrations ofCompound 1 relative to the 29:1 and 0:1 Compound 1:PS samples describedabove. FIGS. 7A through 7D show OM images of irradiated PS filmscontaining 0, 1.7 mM, 7.5 mM, and 24 mM amounts of Compound 1 in PS,respectively. Average roughness of the baked films was determined as afunction of the amount of Compound 1 in the sample from AFM images (seeFIG. 8A). As shown in FIG. 8B, the roughness decreases as the amount ofCompound 1 is increased. A similar trend is found when the correspondingheights of the PS films are plotted against the amount of Compound 1 inthe spin-cast solution (see FIG. 8C). The average height of the annealedfilms decreases as the amount of cross-linker increases, suggesting thatthe irreversible expansion accompanied by heating a thin film aboveT_(g) is attenuated. By adjusting the concentration of Compound 1 in thefilms, the surface topography can be controlled.

Additionally, the dosage of UV light was adjusted. FIG. 9 shows a graphof the average roughness as a function of the irradiation time for asample containing 60:1 of Compound 1:PS. The observed dependence ofsurface roughness on irradiation time is in accord with surfacemodification via photochemical means. As shown, significant decrease inthe roughness of the films is not observed after about 30 minutes ofirradiation.

Additionally, 25 nm films having ratios of 3:1 and 0:1 Compound 1:PSwere spun cast on silicon wafers, irradiated for 1 hour, and annealed at170° C. overnight. FIGS. 10A and 10B show optical microscope (OM) imagesof the 25 nm films having about 3:1 and 0:1 Compound 1:PS, respectively.As shown, 0:1 ratio sample exhibits large hole that are approximately 40μm in diameter while the 3:1 ratio sample does not show such features.

7 nm films having 17:1 and 0:1 ratios of Compound 1:PS were also spuncast on silicon wafers, irradiated for 1 hour, and annealed at 170° C.overnight. FIGS. 11A and 11B show AFM images of the 7 nm films havingabout 17:1 and 0:1 Compound 1:PS, respectively. As shown, 0:1 ratiosamples exhibit large holes that appear to have formed a ribbon whilethe 17:1 ratio samples do not show such features. Decreasing the ratioto 8:1 gave similar results. In contrast to the 25 nm film, a ratio of3:1 is unable to prevent the formation of dewetting morphologies in the7 nm film as evidenced by OM. 2 nm film also needed higher concentrationof Compound 1 to prevent dewetting. Therefore, a greater amount ofcrosslinker may be utilized to stabilize the thinner films.

Dewetting Upon Exposure to Solvent Vapors

Dewetting of polymer films upon exposure to solvent vapors were alsostudied. The 7 nm and 25 nm PS films with and without Compound 1 wereplaced in a flask of saturated toluene vapor at room temperature. Theresulting OM images are shown in FIGS. 12A through 13B.

FIG. 12A shows a 7 nm PS film containing Compound 1 after irradiationand exposure to vapor. FIG. 12B shows a pure 7 nm PS film after exposureto vapor. Films containing irradiated Compound 1 formed holes whereasfilms without Compound 1 or unirradiated films containing Compound 1formed droplets. The droplet formation is suggestive of furtherprogression of dewetting as it is generally considered the final stageof dewetting.

For the 25 nm films, the inhibition of dewetting is more pronounced.FIG. 13A shows an image of a 25 nm PS film containing Compound 1 afterirradiation and exposure to toluene vapor. FIG. 13B shows thecorresponding pure PS film. Once again, droplet formation is observed inthe pure film. Only small imperfections appear in the irradiated film.As the amount of Compound 1 is decreased, the frequency of occurrence ofthese features decreases. The ability of the photocrosslinked film toinhibit film rupture in response to vapor suggests that the inventionmay allow stabilizing thin film devices that respond to chemicalstimuli, such as surface acoustic wave devices that use polymer films assensors for detecting vapors.

Dewetting-Resistant PS Films on Other Surfaces

Films of PMMA were prepared on silicon, followed by deposition of a PSfilm containing Compound 1 (1:17 ratio of PS:Compound 1) on top of thePMMA film. FIGS. 14A and 14B show OM images and FIGS. 14C and 14D showAFM images of PS films on PMMA. As shown in FIGS. 14A and 14C,inhibition of dewetting is observed in the irradiated sample. Theaverage roughness of the crosslinked film is about 0.90±0.1 nm ascompared to the uncrosslinked films shown in FIG. 14B and 14D (16±3 nm).Moreover, the average height of the uncrosslinked film is about 60±18 nmas compared to about 12±8 nm for the crosslinked film. Higher amounts ofCompound 1 relative to PS were needed to see a noticeable inhibition ofdewetting when compared to that observed on the silicon surface. Withoutwishing to be bound by theory, this may be attributed to a change inwettability as the contact angle of PS on Si is about 7.5° whereas thecontact angle on PMMA is about 11.3°.

100 nm gold film was also formed on silicon, followed by deposition of aPS film containing Compound 1 in the sample on top of the gold film.FIGS. 15A through 15C show OM images of an irradiated sample havingCompound 1 (FIG. 15A), an irradiated sample without Compound 1 (FIG.15B), and an unirradiated sample having Compound 1 (FIG. 15C). As shown,the irradiated sample containing Compound 1 (see FIG. 15A) shows lessdewetting than the other two control samples (FIGS. 15B and 15C).

Irradiation Through a Photomask

Additionally, irradiation was carried out using a photomask. As shown inthe OM images of FIG. 16, dewetting occurs in the regions that weremasked from irradiation when the sample was heated to about 170° C. Theresults show that the invention allows for controlling the position ofwhere crosslinks can occur in a thin film.

Example 6 Fabrication of Three-Dimensional Structures

In order to pattern PS dewetting morphologies on a surface, a 30 nmthick PS film containing Compound 1 was irradiated through a photomaskhaving Columbia University's crown logo. The film was then heated in avacuum oven at 170° C. for 5 hours. The resulting pattern is shown inFIG. 17. The light colored regions are regions that have been maskedfrom irradiation. As shown, dewetting is limited only to theunirradiated regions (see dark droplets indicative of dewetting withinthe crown logo). Interestingly, uncrosslinked polymer collects at theedges of the pattern to form a long ribbon of polymer. Typically, suchshapes are unstable and decay due to Rayleigh instabilities. Heating thepatterned surfaces overnight did not result in the decay of the shapes.The interface between cross-linked and uncrosslinked polymer appears tostabilize this structure.

Another feature of interest is the preference for droplet formation onthe larger masked areas. Both the base of the crown and the middle barshow a more regular presentation of droplets as opposed to the thinnerregions of the pattern.

Microchannels of varying widths were also patterned. Irradiating andheating this sample as above resulted in the pattern shown in FIG. 18.The smallest channel has a width of approximately 20 μm. As describedabove, the various confinement regimes affect the dewetting behavior ondifferent length scales. When the dewetted region is confined to a widthof 47 μm, droplets do not form regularly. The next largest width, 86 μm,shows a regular arrangement of droplets throughout the pattern. Thespacing appears to be too small for the typical arrangement of hexagonsto develop because the dewetting width is jammed into a volume smallerthan the size of the conventional pattern. As the dewetting widthincreases, the morphology of the ribbon begins to deviate from astraight-edge with bulges appearing regularly throughout.

Another feature of interest is the height of the matter that collects atthe wall of the channel. The effect of the channel width on the heightof the channel walls is illustrated in the graph in FIG. 19. The heightof the walls increased as the width of the channel increases owing tomore matter collecting at the interface. In these experiments, themaximum height was approximately 100 μm and was reached when the maskwidth was 24 μm. Increasing the mask width did not increase the heightof the walls beyond 100 μm. The average diameter of a droplet for a filmof this thickness is 25±6 μm. The height of the film increases sharplywhen the size of the pattern in the photomask is in this range. Apattern of 19 μm gives a height of only 28±2 μm.

FIG. 20 displays a pattern of larger channels. As the width of thechannels increase, the droplets evolve towards a polygonal patterntypical of PS dewetting in films of this thickness. As noted above, thewidth of a typical polygon for this film thickness is 280±20 μm. As thewidth of the dewetting region decreases the pattern formation isdisrupted, resulting in branched, zigzag and linear assemblies ofdroplets. Another feature of interest is the width of the ribbon betweenthe channels. As the width of the cross-linked area is decreased, thewidth of the ribbon that assembles at the interface decreases. Thissuggests that the uncross-linked PS localizes itself on the crosslinkedPS when heated above T_(g).

An interesting characteristic of thin polymer films is the change inproperties with a change in size. For example, it has been suggestedthat the mechanism by which dewetting occurs is dependent on thethickness of the film. For films of less than 10 nm, spinodal dewettinghas been attributed to the rupture of the film whereas films greaterthan 10 nm are said to dewet by nucleation onto defect sites. The effectof film thickness on the confined dewetting behavior was examined. FIG.21A displays an OM image of a patterned 7 nm film treated under the sameconditions as above. The matter confined within the bars of the image(FIG. 21B) takes up a different shape than the droplets that appear inthe larger circular rim of the pattern (FIG. 21C). The size of thedewetting regions within the checkerboard pattern is approximately 50μm. The vertical structures at the interface of the crosslinked anduncrosslinked regions did not form for the 7 nm film, as they did forthe 30 nm films.

In order to visualize the edge of the pattern we obtained AFM images ofthe surface. FIG. 22 shows an AFM image of the edge of a channel withina patterned 7 nm film. Three distinct structural regions are evidentfrom this image: 1) the uncrosslinked region showing a bicontinuousspinodal-like pattern, 2) the interphase region between the cross-linkedand uncrosslinked film and 3) the smoother crosslinked area. Theundulating pattern in the uncrosslinked region is reminiscent ofspinodal dewetting. This area of the surface has the greatest amount ofsurface area and the highest peaks. Peaks as high as 95 nm were found inthis region. Heights at least as small as 20 nm were also found withinthe curved walls. The second area of interest, the interphase region,displays many circular holes. As the interphase bleeds into theuncrosslinked area, the holes grow and coalesce until the undulatingpattern is reached. As the interphase region approaches the crosslinkedarea, the holes shrink and the surface roughness ultimately appears moreconstant. Our interphase region is analogous to the theoreticalinterphase between two surfaces in which there is a change in density ofmaterial between two distinct phases. Our macroscopic interphase couldbe a result of a change in crosslink density due to scattering ofphotons into the edges of the masked region or a change in elasticity asthe crosslinked polymer approaches the uncrosslinked polymer. The finalarea of interest is the crosslinked film. This part of the film resistsdewetting and has smaller surface features (approximately 5 nm) comparedto the interphase and uncrosslinked phase.

The crosslinked polymer can act as a microvessel/microvial that confinesthe uncrosslinked polymer to a defined space. Heating such a systemabove T_(g) results in the formation of smaller patterns within thelarger pattern. The structures of the smaller patterns can be controlledby changing the size of the larger pattern.

Example 7 Photochemical Immobilization of Carbohydrates

In order to create a novel surface suitable for immobilizingcarbohydrates, Compound 4 was self-assembled on, glass (Arraylt),silicon (Wafer World) and quartz (SPI) in anhydrous toluene to produceSAM 4 as follows (see FIG. 3). Substrates and glassware were cleaned byboiling in a “piranha” solution (7:3 sulfuric acid:H₂O₂) for one hourfollowed by an extensive rinse with water and methanol. Substrates weredried with a stream of argon and immersed in a 1 mmol solution ofcompound 1 in anhydrous toluene (Aldrich). The solution was kept underargon and left undisturbed for twelve hours. The surface was thenremoved and baked for two hours at 110° C. The resulting self-assembledmonolayers were rinsed with toluene and sonicated three times for twominutes each in toluene, toluene:methanol 1:1, and methanol. Substrateswere kept in argon-purged vials until further use.

The self-assembly of Compound 4 on the surface was verified by theUV/Vis spectroscopy. FIG. 23 shows the UV/Vis spectrum of Compound 4 inethanol (dashed line) and after forming SAM 4 (solid line). Assuming theextinction coefficient of the chromophore on the surface is the same asin solution, the approximate surface coverage was calculated to be 5.5molecules per nm². A calculation using Chem3D® suggests about 4.9aliphatic phthalimides can fit in a space of 1 nm², a value that is thesame order of magnitude as the experimental value, suggesting that SAM 4is densely packed.

In order to test the ability of surface bound phthalimides tophotochemically immobilize sugars, FITC-conjugated polysaccharide filmswere spin-coated onto SAM 4 and irradiated with a medium pressuremercury lamp in an inert environment (dashed line). The fluoresceinisothiocyanate (FITC)-conjugated α(1,6)dextrans weighing 20 kD or 2000kD (Dextran-FITC) (Sigma) were spin-coated from a 10 mg/ml aqueoussolution at 3000 RPM for 90 seconds and placed in argon purged quartztubes. Irradiation was carried out with a Rayonet Photochemical Reactorequipped with lamps that emit at 300 nm. For ellipsometry andfluorescence experiments, the surface was rinsed by placing in H₂O for12 hours followed by rinsing with methanol. Substrates were blown drywith argon.

Two controls were also prepared similarly as described above. In thefirst, polysaccharides were spin-coated onto SAM 4 and left in the dark(dotted line). In the second, polysaccharides were spin-coated onto anunderivatized silicon wafer (straight line). All three samples wereplaced in water filled vials for twelve hours. After removing thesamples and rinsing with water and methanol followed by blow-drying withargon, the fluorescence spectra of each sample were obtained as shown inFIG. 24. Preferential retention of polysaccharides on the irradiatedsample relative to the two controls indicates photochemicalimmobilization of the polysaccharides on SAM 4.

The film thicknesses of the three samples were measured using aBeaglehole ellipsometer in variable angle mode. A refractive index valueof 1.5 was used for the organic layer. As shown in Table 1, theirradiated sample retains 7.1±0.3 nm of material after the rinse. Thethickness of the material on the SAM kept in the dark was 0.7±01.3 nmand the thickness on the underivatized silicon wafer was 0.4±0.3 nm. Thereported thicknesses do not include the thickness of the SAM (1.2 nm).The surfaces were further investigated with water contact anglemeasurements. The hydrophilic nature of the sugars reduced the watercontact angle from 65±1° to 28±1° on the irradiated SAM. Inefficientimmobilization on the dark control is evident from a post-rinse contactangle of 62±1°. The higher retention of material on the irradiated SAMdemonstrates that self-assembled phthalimide monolayers are capable ofphotochemically bonding to an overlayer carbohydrate film despite anyspatial restrictions on the chromophore as a result of placement in aconstrained environment. We speculate that the nature of the bonding iscovalent and results from radical-radical combination following hydrogenabstraction.

TABLE 1 Thickness and H₂O contact angles of photochemically graftedpolysaccharide films after rinsing with H₂O for 12 hours. Contact AngleContact Thickness after Before Casting Angle After Sample Rinse (nm)Carbohydrate Film Rinse Compound 2 7.1 ± .3 65 ± 1° 28 ± 1° SAM2/Sugars/hv Compound 2 0.7 ± .3 65 ± 1° 62 ± 1° SAM 2/Sugars/dark NoSAM/Sugars 0.4 ± .3 65 ± 1° 23 ± 1°

The above experiments were also performed on self-assembled monolayershaving benzophenone chromophores, another class of aromatic carbonylsthat can photochemically abstract hydrogen from C—H groups and have beenshown to graft polymers to surfaces. The resulting carbohydrate filmthickness and fluorescence intensity were lower and the contact anglewas higher than the films on SAM 4. Without wishing to be bound bytheory, the lower performance may be due to the radical center in thebenzophenone SAM occurring further from the surface than in thephthalimides, self-quenching of the excited state or a higherinterfacial tension between the more hydrophobic benzophenone monolayerand the carbohydrate film in comparison to the phthalimide-carbohydrateinteraction. Benzophenone SAMs have more hydrophobic character than SAM4 (phthalimide SAM) as evidenced by a higher water contact angle ofabout 85°. Preliminary experiments with a microarray spotter have shownthat hydrophilic surfaces are more easily spotted than hydrophobicsurfaces. In any case, other photoactive carbonyl groups capable ofabstracting hydrogen atoms can be substituted and may enhance or retardthe reaction due to the efficiency of self-assembly, steric andenergetic constraints.

In addition to covalently attaching underivatized sugars to a surface,patterns of grafted sugars were also generated, which is schematicallyshown in FIG. 25. A 75 mesh TEM grid (Electron Microscopy) was used as aphoto-mask for all patterning experiments. Dextran-FITC 2000 kD and 20kD polysaccharide films were prepared as described above. Glucose(Aldrich) was spin-coated from a solution of 26 mg in 1 ml ofacetonitrile at 3000 RPM for 90 seconds. One drop of a sucrose (Aldrich)solution containing 1.5 g in 1 ml H₂O was placed on a surface using apipette. Approximately ¾ of the drop was removed with a pipette. In allcases, the photomask was placed on top of the carbohydrate film ordroplet and pressed down with a quartz plate. Irradiation was carriedout in an argon filled glove box with a desktop lamp containing a 300 nmRayonet lamps for approximately 2 hours. The photoreaction wasrestricted to the transparent regions of the mask leaving the pattern ofthe mask written to the surface via attached carbohydrates. Samples wererinsed by sonicating in H₂O for 15 minutes, changing the water and vialevery 5 minutes. Sonication was accompanied by extensive rinsing withwater and methanol. Samples were blown dry with argon.

Patterns were visualized by condensing water onto the pattern andimaging with a Nikon Eclipse optical microscope equipped with an INSIGHTdigital camera. Two methods were used to condense water onto thesurface. In the first, the surface was exposed to an extended breath. Inthe second, the surface was held over boiling water. FIGS. 26A and 26Bshow water condensation images of the resulting patterns obtained frompolysaccharides with a molecular weight of 2000 kD. FIG. 26A wasobtained by breathing onto the sample and FIG. 26B was obtained byholding the sample over a beaker of boiling water for approximately 15seconds. In both cases, hydrophilic attraction between water and thepolysaccharides relative to the unmodified masked regions of themonolayer causes water to preferentially reside on the areas of thesurface containing polysaccharide. The results were similar when 20 kDpolysaccharides were patterned.

As described above, other studies suggested that the immobilizationefficiency decreases with the decreasing molecular weight of thecarbohydrate. In order to show the versatility of the invention, glucoseand sucrose, two simple sugars at the extreme of low molecular weightcontaining both six and five member carbohydrate moieties, were tested.The resulting water condensation images are presented in FIGS. 27A and27B. The visible patterns show that the invention is capable ofimmobilizing sugars of the lowest molecular weights.

As shown, the invention requires no chemical modification of the sugarsprior to deposition. Further, because covalent attachment is involved,sugars of all molecular weights can be immobilized, whereas sugars oflower molecular weights were more prone to be washed away in theconventional art. The photochemical nature of the technique allowssimple arrays to be created without a robot and makes the methodadaptable to the full potential of photolithography, which is currentlyused in industry for the high-throughput fabrication of computer chipsand nanoscale patterning. Multiple carbohydrate patterns can beimmobilized by repeating the reaction with a different carbohydrate in apreviously masked region. In conjunction with a microarray spotter,large libraries of carbohydrates can be immobilized on surfaces. Theversatility and ease of the method provides an opportunity forbiologists, chemists and engineers to investigate and create newbiological materials.

Instrumental Measurements

UV-vis spectra were obtained using a Shimadzu (UV-2401PC) UV-visrecording spectrophotometer. Contact angle measurements were performedwith a Rame-Hart 100-00 contact angle goniometer using Millipore Milli-Qwater. At least three droplets were measured on each sample andaveraged. Thicknesses were measured with a Beaglehole ellipsometer invariable angle mode. A refractive index of 1.5 was used for all samples.Measurements were performed three times in different locations on thesurface and averaged. Fluorescence spectra were obtained using a JobinYvon Fluorolog 3 spectrofluorimeter in front face mode. The surface wasplaced at an angle of 20° to a line parallel to the plane of thedetector.

Example 8 Fabrication of Mixed Monolayers

As schematically shown in FIG. 28A, mixed monolayers were formed from asolution containing a 5:1 ratio of aminopropyltrimethoxy silane toCompound 4 (SAM 4A). SAM 4A was made in the same manner as SAM 4, exceptthat a 5× molar amount of aminopropyltrimethoxy silane (Gelest) wassimultaneously added with Compound 4. The contact angle of the resultingsurface was 72±1°.Without wishing to be bound by theory, the hydrophilicamine group can interact more favorably with the carbohydrates ascompared to the more hydrophobic phenyl ring of Compound 4, decreasingthe interfacial tension between the carbohydrate and the surface, andallowing for increased amounts of carbohydrates to be adsorbed to thesurface for subsequent photo-immobilization. It should be noted that SAM4A may be a multilayer rather than a monolayer.

Microarrays were robotically prepared as follows. Antigen preparationswere dissolved in saline (0.9% NaCl) at a given concentration and werespotted as triplet replicate spots in parallel. The initial amount ofantigen spotted was 0.35 ng per spot and diluted by serial dilutions of1:5 thereafter (See also microarray images inserted in FIG. 19). Ahigh-precision robot designed to produce cDNA microarrays (PIXSYS 5500C,Cartesian Technologies Irvine, Calif.) was utilized to spot carbohydrateantigens onto chemically modified glass slides as described. Both FASTSlides (Schleicher & Schuell, Keene, N.H.) and SAM 4A slides werespotted. The printed FAST slides were air-dried and stored at roomtemperature. The printed SAM 4A slides were subjected to UV irradiationin order to activate the photo-coupling of carbohydrates to the surface.

After microarray spotting, the SAM 4A slides were air-dried and placedin a quartz tube. The sealed tube was subsequently purged with argon ornitrogen before irradiation. UV irradiation was conducted by placing thequartz tube under a desktop lamp containing a 300 nm Rayonet bulb forone hour. Precaution was made to avoid skin and eye contact with theradiation during the irradiation process.

FIGS. 29A and 29B show the results after spotting SAM 4A using threefluorescein isothiocyanate (FITC)-conjugated α(1,6)dextrans withmolecular weights (MWs) of 20, 70 and 2000 kDa, respectively. In theseexperiments, the amount of polysaccharides spotted on the surfaces wasmonitored by measuring the FITC signals associated with the carbohydratearrays before irradiation (see FIG. 29A). By examining the fluorescentsignals before treatment (FIG. 29A), it was determined that the amountsof carbohydrates adsorbed onto SAM 4A after spotting are significantlyless than those spotted on the FAST slide. Without wishing to be boundby theory, this may be attributed to the two-dimensional nature of SAM4A, which allows less polysaccharides to be delivered and adsorbed incomparison to nitrocellulose surfaces that involve thickerthree-dimensional coatings.

Then, the printed microarrays were rinsed and washed with PBS (PH 7.4)and with 0.05% Tween 25 times with five minutes of incubation in eachwashing step. They were then “blocked” by incubating the slides in 1%BSA in PBS containing 0.05% NaN3 at room temperature (RT) for 30minutes. Antibody staining was conducted at RT for one hour at givendilutions in 1% BSA PBS containing 0.05% NaN₃ and 0.05% Tween 20.Determination of immobilized polysaccharides on the surface afterirradiation and extensive washing was performed by staining the arraysusing a biotinylated anti-α(1,6)dextran monoclonal antibody, 16.4.12E.This antibody is specific for the terminal non-reducing end epitopesdisplayed by all three dextran-conjugates immobilized on the surface.Since a biotinylated anti-dextran antibody (mAb 16. 4.12E) was appliedin this study, streptavidin-Cy3 conjugate (Amersham Pharmasia) withwavelengths of excitation and emission at 552 and 570 nm, respectively,was applied to reveal the bound anti-dextran antibodies. The stainedslides were rinsed five times with PBS and with 0.05% Tween 20 aftereach staining step. A ScanArray 5000A Standard Biochip Scanning System(PerkinElmer, Torrance, Calif.) equipped with multiple lasers, emissionfilters and ScanArray Acquisition Software was used to scan themicroarray. Fluorescence intensity values for each array spot and itsbackground were calculated using ScanArray Express (PerkinElmer,Torrance, Calif.). A nitrocellulose substrate (FAST), an establishedplatform, was similarly treated to provide a comparative data.

The results illustrated in FIG. 29B demonstrate that SAM 4A retains asimilar amount of material regardless of the molecular weight of thepolysaccharides spotted. Neither an underivatized glass surface nor SAM4A without UV irradiation showed a detectable signal after treatmentwith anti-α(1,6)dextran antibodies. These results were reproduced inmultiple microarray assays. Thus, not only is SAM 4A suitable for use inthe high-throughput construction of microarrays, but also thephoto-immobilized carbohydrates retain their immunological properties,as defined by a specific antibody, after immobilization. These resultsshow that the invention offers a plausible alternative to nitrocellulosefor displaying lighter carbohydrates.

A panel of mono- and oligosaccharide arrays on SAM 4A and FAST slideswere also studied. The spotted arrays were probed with a biotinylatedlectin ConA (see FIG. 29C), which is Man- and/or Glc-specific andrequires the C-3, C-4 and C-5 hydroxyl groups of the Man or Glc ring forbinding. The results showed that oligosaccharides with three (IM3), five(IM5) and seven glucoses (IM7) are reactive to ConA on the SAM 4A slidebut not on the FAST slide. However, none of the spotted mono-saccharideswas reactive to the lectin on these surfaces. The method ofphoto-coupling, which can target any CH-group on the carbohydrate ringswith varying specificity depending on the structure of the ring, mayinterfere significantly with the lectin binding of mono-saccharides, Manor Glc. The limited specificity of the reaction and the lesser amount ofcarbohydrate epitopes present for smaller carbohydrates reduces theprobability that a biologically-active epitope presents itself at theair-monolayer interface.

Mixed monolayers were formed from a solution containing a 20:1 ratio ofaminopropyltrimethoxy silane to Compound 4 (SAM 4B). The 20:1 ratio ofaminopropyltrimethoxy silane to Compound 4 was mixed in a vialcontaining anhydrous toluene. A microscope slide was placed in a vial,sealed, and purged with argon. The prepared solution was added into thesealed vial via a syringe and allowed to react overnight. The slide wasthen removed and rinsed as described above. As shown in FIG. 30, SAM 4Bmay be in the form of a multilayer rather than a monolayer.

A FAST slide and a SAM 4B slide were spotted with a panel ofcarbohydrates (38 total) and protein/peptide (8) preparations, as shownin FIGS. 31A and 31B. The slides were then stained with a preparation ofhuman serum (1:25 dilution). The chip-bound human IgG antibodies wererevealed with an anti-human IgG antibodies conjugated with Cy3. Themicroarray images were captured using ScanArray 5000A microarrayscanner. As shown in FIG. 31A, the photo-generated carbohydrates usingSAM 4B reveal a broader spectrum of IgG anti-carbohydrate antibodies ascompared to the FAST slide.

As shown in FIGS. 31A and 31B, broader spectrum of IgG anti-carbohydrateantibodies were observed with SAM 4B as compared to those prepared onFAST slides.

Example 9 Immobilization of Polymers on Surfaces

In addition to immobilization of various carbohydrates, variety ofpolymers were also immobilized and patterned on a surface. PS,poly(tert-butyl acrylate) (PTBA), and poly(vinyl alcohol) PVA wereimmobilized and patterned on SAM 4. The OM images of the immobilizedPVA, PTBA, and PS patterns are shown in FIGS. 32A through 32C,respectively. PVA was imaged by breath condensation. PTBA and PS wereimaged by spin coating a mixture of PS and triphenylsuphonium triflateonto the patterned surface.

To test for the robustness of the immobilized films, surfaces with PVAwere irradiated for various time periods to obtain differentthicknesses. The surfaces immobilized with PVA were rinsed in hot waterafter irradiation. The immobilized surfaces were placed in a vial ofdeionized water and heated to 75° C. for 15 minutes and to 90° C. for2.5 hours. The deionized water was changed and the surface was rinsedwith deionized water. Surfaces were then placed back into a heated water(about 95° C.) for additional three hours. FIG. 33 shows a plot of thethickness as a function of irradiation time after the hot watertreatment. As shown, PVA remain immobilized on the surface after heattreatment and exhibit an increase in thickness with increasingirradiation time.

Example 10 Electroless Deposition of Metals

Moreover, electroless deposition of nickel was carried out toselectively deposit nickel on regions immobilized with polyacrylic acid(PAA). A glass surface was coated with SAM 4 and PAA (35 wt % in water)was spin-coated onto SAM 4 as described above. Then, the sample wasirradiated through a photomask having lines of varying widths for about4 to 5 hours. The sample was then rinsed with water and immersed in aaqueous catalyst solution containing 5 mM palladium tetraammoniumdichloride for about 30 seconds. The sample was then removed and placedin deionized water for about 30 seconds to rinse off any catalyst thatare not on the regions coated with PAA. The sample was then placed in anickel bath for 15 minutes. The nickel bath contained 4 g of nickelsulfate, 2 g sodium citrate, 1 g of lactic acid, 0.2 g of dimethyl amineborane, and 100 mL of deionized water. The pH of the nickel bath wasadjusted to 6.8±0.2 using ammonium hydroxide.

FIG. 34 shows that nickel was selectively deposited onto only the PAAcoated regions.

As various changes can be made without departing from the scope andspirit of the invention as described, it is intended that all subjectmatter contained in the above description, shown in the accompanyingdrawings, or defined in the appended claims be interpreted asillustrative, and not in a limiting sense.

1. A method for forming a dewetting-resistant surface, the methodcomprising: depositing a molecule to at least a part of the surface,wherein the molecule is a polymer selected from the group consisting ofpolystyrene, polyether, polyester, polyamide, polyvinyl, polysaccharide,and mixtures thereof; depositing a photoactive compound which comprisesa compound of formula (I)

and/or a compound of formula (II)

and irradiating the photoactive compound to obtain thedewetting-resistant surface, wherein: n is an integer from 1 to 1000; Yis independently —CH₂—, —C(O)—, —OC(O)—, —C(O)O—, —C(O)NR³—, or—NR³C(O)—; each of the rings A, B, C, D, E, and F is substituted withone or more R₁ groups; R₁ is independently a hydrogen, a halogen, ahydroxyl, an aryl, an amide, a cyano, a substituted or unsubstitutedstraight- or branched-chain alkyl which contains 1 to 6 carbons, asubstituted or unsubstituted alkene which contains 2 to 4 carbons, asubstituted or unsubstituted alkyne which contains 2 to 4 carbons,—C(O)R³, —CO₂R³, —OC(O)R³, —OR³, or —OC(O)R⁵; R³ is independently ahydrogen, a substituted or unsubstituted C₁-C₁₀ straight-chain orbranched-chain alkyl, or a substituted or unsubstituted alkene; and R⁵is independently a hydrogen, an unsubstituted straight- orbranched-chain alkyl that contains 1-6 carbons, or a straight- orbranched-chain alkyl that contains 1-6 carbons and is substituted by analkyne.
 2. The method of claim 1, wherein said irradiating is carriedout with at least one wavelength from about 290 to about 350 nm.
 3. Themethod of claim 1, wherein the surface comprises an inorganic material,an organic material, a second polymer, silicon, wafers, or combinationsthereof.
 4. The method of claim 3, wherein the photoactive compound is


5. (canceled)
 6. The method of claim 4, wherein said depositing thephotoactive compound is carried out using a robotic spotter to obtain apattern of crosslinked polymer and uncrosslinked polymer after saidirradiation.
 7. The method of claim 4, wherein said irradiating iscarried out through a photomask having a desired pattern to obtain apattern of crosslinked polymer and uncrosslinked polymer after saidirradiation.
 8. The method of claim 7, further comprising heating thesurface to a temperature above the glass transition temperature or themelting temperature of the polymer.
 9. The method of claim 8, wherein atleast a portion of the uncrosslinked polymer has migrated to theinterface of the crosslinked polymer and the uncrosslinked polymer toform a vertically rising structure.
 10. The method of claim 3, whereinthe photoactive compound is


11. (canceled)
 12. The method of claim 10, wherein said depositing thephotoactive compound is carried out using a robotic spotter to obtain apattern of crosslinked polymer and uncrosslinked polymer after saidirradiation.
 13. The method of claim 10, wherein said irradiating iscarried out through a photomask having a desired pattern to obtain apattern of crosslinked polymer and uncrosslinked polymer after saidirradiation.
 14. The method of claim 13, further comprising heating thesurface to a temperature above the glass transition temperature or themelting temperature of the polymer.
 15. The method of claim 14, whereinat least a portion of the uncrosslinked polymer has migrated to theinterface of the crosslinked polymer and the uncrosslinked polymer toform a vertically rising structure.